The Preparation Of Fe₂O₃ Complex And Their Electrochemical Performance

Due to the rapid development of science and technology,the demand for energy is increasing and the demand is also higher.As an excellent secondary battery,lithium ion battery has attracted more and more attention in recent years because of its superior characteristics such as recyclability,convenience and high capacity.In this paper,MgFe₂O₄/Fe₂O₃?Mg_1-xCa_xFe₂O₄/Fe₂O₃?Zn_1-xCa_xFe₂O₄/Fe₂O₃ were prepared and their physical characterization and electrochemical properties were tested.The specific contents include:1.MgFe₂O₄/Fe₂O₃ composite materials were prepared by solvothermal and high temperature calcinations,using Fe?OH?₃ as the iron source,the molar ratio of iron magnesium source to magnesium source was 5:2 and solvent was deionized water and ethylene glycol with a volume ratio of 1:1.Solvent heat temperature of 180?,time of 24 h;Calcination temperature is 600?,time of 4 h.The optimum composition and preparation conditions of the material were obtained by orthogonal experiment.Physical characterization of the material was carried out by means of XRD,SEM,BET,etc.The electrochemical properties were studied with lithium metal as the counter electrode.When the current density was 0.5 A g^-1,the initial discharge specific capacity was 966 mAh g^-1,and 65%of the initial discharge specific capacity was maintained after 400 cycles.Compared with MgFe₂O₄ and Fe₂O₃ materials,MgFe₂O₄/Fe₂O₃ composite improves the electrochemical properties of pure phase materials.2.Mg_1-xCa_xFe₂O₄/Fe₂O₃ composites were prepared by solvothermal and high temperature calcinations,using Fe?OH?3 as the iron source,Mg?OH?2 as the magnesium source,Ca?OH?₂ as the calcium source and solvent was deionized water and ethylene glycol with a volume ratio of 1:1.Solvent heat temperature of 180?,time of 24 h.Using orthogonal experiment,when X=1/3,the molar ratio of Mg_1-xCa_xFe₂O₄:Fe₂O₃ is 2:3,calcination temperature is 600?,calcination time is 4h,the materials exhibited the best electrochemical properties.The morphology of the material was characterized by SEM and TEM,and the material was composed of nanoparticles of 50¹50 nm.The electrochemical properties were studied with lithium metal as the counter electrode.When the current density was 0.5 A g^-1,the initial discharge specific capacity was 1037 mAh g^-1,and 62%of the initial discharge specific capacity was maintained after 600 cycles.3.Zn_1-xCa_xFe₂O₄/Fe₂O₃ composites were prepared by solvothermal and high temperature calcinations,using Fe?OH?3 as the iron source,Zn?OH?2 as the zinc source,Ca?OH?₂ as the calcium source and solvent was deionized water and ethylene glycol with a volume ratio of 1:1.Solvent heat temperature of 180?,time of 24 h.Using orthogonal experiment,when X=1/3,the molar ratio of Zn_1-xCa_xFe₂O₄:Fe₂O₃ is1:1,calcination temperature is 600?,calcination time is 4h,the materials exhibited the best electrochemical properties.XRD and XPS were used to characterize the phase and element types of the materials,Zn_1-xCa_xFe₂O₄/Fe₂O₃ composite was successfully synthesized.The electrochemical properties were studied with lithium metal as the counter electrode.When the current density was 0.5 A g^-1,the initial discharge specific capacity was 1263 mAh g^-1,and 37%of the initial discharge specific capacity was maintained after 650 cycles.